def chisl(s):
    k = ''
    if s == 'zero': k = '0'
    elif s == 'one': k = '1'
    elif s == 'two': k = '2'
    elif s == 'three': k = '3'
    elif s == 'four': k = '4'
    elif s == 'five': k = '5'
    elif s == 'six': k = '6'
    elif s == 'seven': k = '7'
    elif s == 'eight': k = '8'
    elif s == 'nine': k = '9'
    return k

prost = [101,103,107,109,113,127,131,137,139,149,151,157,163,167,173,179,181,191,193,197,199,211,223,227,229,233,239,241,251,257,263,269,271,277,281,283,293,307,311,313,317,331,337,347,349,353,359,367,373,379,383,389,397,401,409,419,421,431,433,439,443,449,457,461,463,467,479,487,491,499,503,509,521,523,541,547,557,563,569,571,577,587,593,599,601,607,613,617,619,631,641,643,647,653,659,661,673,677,683,691,701,709,719,727,733,739,743,751,757,761,769,773,787,797,809,811,821,823,827,829,839,853,857,859,863,877,881,883,887,907,911,919,929,937,941,947,953,967,971,977,983,991,997]
try:
    s1, s2, s3=input().split()
    a1,a2 = 0,0
    num = int(chisl(s1)+chisl(s2)+chisl(s3))
    for x in range(len(prost)):
        if prost[x]>num:
            a2 = x
            a1 = x-1
            break
        
    if abs(prost[a1] - num) > prost[a2] - num:
        print(prost[a2])
    elif abs(prost[a1] - num) <= prost[a2] - num:
        print(prost[a1])
except:
    print('Wrong answer')